U.S. patent application number 16/069093 was filed with the patent office on 2019-01-17 for antenna apparatus.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Yoshio INASAWA, Michio TAKIKAWA, Takashi TOMURA.
Application Number | 20190020118 16/069093 |
Document ID | / |
Family ID | 59685071 |
Filed Date | 2019-01-17 |
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United States Patent
Application |
20190020118 |
Kind Code |
A1 |
TOMURA; Takashi ; et
al. |
January 17, 2019 |
ANTENNA APPARATUS
Abstract
A plurality of primary radiators (1) is classified by
combinations of frequency and polarization of radiated radio waves,
a plurality of primary radiators (1) belonging to the same class is
arranged at positions corresponding to vertexes of one of triangles
in a repeated triangle pattern TR.sub.Pattern, and the shape of a
main reflector (2) and the shape and arrangement of the repeated
triangle pattern TR.sub.Pattern are determined such that a
direction of a line segment passing through positions corresponding
to two vertexes in the triangle is different from a radiation
direction of a sidelobe of a radio wave reflected by a main
reflector (2) after having been radiated from a primary radiator
(1) arranged at a position corresponding to the vertexes.
Inventors: |
TOMURA; Takashi; (Tokyo,
JP) ; TAKIKAWA; Michio; (Tokyo, JP) ; INASAWA;
Yoshio; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
59685071 |
Appl. No.: |
16/069093 |
Filed: |
February 26, 2016 |
PCT Filed: |
February 26, 2016 |
PCT NO: |
PCT/JP2016/055877 |
371 Date: |
July 10, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q 19/192 20130101;
H01Q 1/288 20130101; H01Q 19/19 20130101; H01Q 19/17 20130101; H01Q
25/007 20130101 |
International
Class: |
H01Q 19/19 20060101
H01Q019/19; H01Q 25/00 20060101 H01Q025/00 |
Claims
1. An antenna apparatus comprising: a plurality of primary
radiators for radiating radio waves; and a main reflector for
reflecting the radio waves radiated from the plurality of primary
radiators, wherein the plurality of primary radiators is classified
by combination of frequency and polarization of the radiated radio
waves, a plurality of primary radiators belonging to a same class
is arranged, in a repeated triangle pattern in which a triangle is
arranged repeatedly, at positions corresponding to vertexes of each
triangle, and a shape of the main reflector and a shape and
arrangement of the repeated triangle pattern are determined such
that a direction of a line segment passing through positions
corresponding to two vertexes in the triangle is different from a
radiation direction of a sidelobe of a radio wave that is radiated
from primary radiators arranged at positions corresponding to the
vertexes and is reflected by the main reflector.
2. The antenna apparatus according to claim 1, wherein an aperture
shape of the main reflector is a parallelogram, and the repeated
triangle pattern includes one or more triangles so as to form a
same shape as the aperture shape.
3. The antenna apparatus according to claim 1, wherein an aperture
shape of the main reflector is a hexagon, and the repeated triangle
pattern includes one or more triangles so as to form a same shape
as the aperture shape.
4. The antenna apparatus according to claim 1, wherein an aperture
shape of the main reflector is a triangle, and the repeated
triangle pattern includes one or more triangles so as to form a
same shape as the aperture shape.
5. The antenna apparatus according to claim 1, wherein each of the
plurality of primary radiators includes a plurality of radiating
elements, and the antenna apparatus further comprises a beam
forming circuit for exciting the plurality of radiating
elements.
6. The antenna apparatus according to claim 1, further comprising a
secondary reflector for reflecting the radio waves radiated from
the plurality of primary radiators toward the main reflector.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to antenna apparatuses for
forming multiple beams.
BACKGROUND ART
[0002] In recent years, research and development of satellite
communication technology using antenna apparatus have been under
way. In order to achieve high-speed communications, it is necessary
to use an antenna apparatus with high gain and low
interference.
[0003] To achieve high gain, antenna apparatuses of a system in
which a service area is covered with a plurality of spot beams have
been studied. In the system of covering a service area with a
plurality of spot beams, it is possible to achieve higher gain than
in the case of a general contoured beam antenna.
[0004] As to interference, which is generally evaluated by
carrier-to-interference ratio (C/I), adjacent beams typically use
different frequencies or polarizations to achieve low interference.
That is, multiple combinations of frequency and polarization are
prepared such that adjacent beams do not use the same combination
of frequency and polarization.
[0005] As a result, interference between adjacent beams can be
suppressed. However, interference may occur between beams using the
same combination of frequency and polarization.
[0006] In an antenna apparatus disclosed in the following Patent
Literature 1, interference waves are reduced by using multiple
antenna elements to form one beam and using different excitation
coefficients for the multiple antenna elements.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: JP 2009-171308 A
SUMMARY OF INVENTION
Technical Problem
[0008] Since the conventional antenna apparatuss are configured as
described above, there is a problem that, even though interference
can be suppressed between desired two beams out of a plurality of
beams having the same combination of frequency and polarization can
be suppressed, it is difficult to suppress interference among all
the beams having the same combination of frequency and
polarization.
[0009] Embodiments of the present disclosure have been devised in
order to solve the problem as described above, and it is an object
of the present disclosure to provide an antenna apparatus capable
of suppressing interference among all the beams having the same
combination of frequency and polarization.
Solution to Problem
[0010] An antenna apparatus according to the present disclosure
includes: a plurality of primary radiators for radiating radio
waves; and a main reflector for reflecting the radio waves radiated
from the plurality of primary radiators, wherein the plurality of
primary radiators is classified by combination of frequency and
polarization of the radiated radio waves, a plurality of primary
radiators belonging to a same class is arranged, in a repeated
triangle pattern in which a triangle is arranged repeatedly, at
positions corresponding to vertexes of each triangle, and a shape
of the main reflector and a shape and arrangement of the repeated
triangle pattern are determined such that a direction of a line
segment passing through positions corresponding to two vertexes in
the triangle is different from a radiation direction of a sidelobe
of a radio wave that is radiated from primary radiators arranged at
positions corresponding to the vertexes and is reflected by the
main reflector.
Advantageous Effects of Invention
[0011] According to the present disclosure, a plurality of primary
radiators is classified by combination of frequency and
polarization of the radiated radio waves, a plurality of primary
radiators belonging to the same class is arranged at positions
corresponding to vertexes of one of triangles in a repeated
triangle pattern in which a triangular shape is repeated, and a
shape of the main reflector and a shape and arrangement of the
repeated triangle pattern are determined such that a direction of a
line segment passing through positions corresponding to two
vertexes in the triangle is different from a radiation direction of
a sidelobe of a radio wave reflected by the main reflector after
having been radiated from a primary radiator arranged at a position
corresponding to the vertexes. Therefore, the effect of suppressing
interference among all the beams having the same combination of
frequency and polarization can be obtained.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a configuration diagram illustrating an antenna
apparatus according to First Embodiment of the present
disclosure.
[0013] FIG. 2 is a diagram showing an illustrative example of
arrangement of primary radiators 1 of the antenna apparatus
according to First Embodiment of the present disclosure.
[0014] FIG. 3 is an explanatory diagram illustrating an example of
combinations of frequency and polarization corresponding to
labels.
[0015] FIG. 4A is an explanatory diagram illustrating a repeated
triangle pattern TR.sub.Pattern in which three triangular shapes
TR.sub.P1, TR.sub.P2, and TR.sub.P3 are arranged in the horizontal
direction, FIG. 4B is an explanatory diagram illustrating a
repeated triangle pattern TR.sub.Pattern in which the two
triangular shapes TR.sub.p1 and TR.sub.P3 are arranged in the
horizontal direction and two triangular shapes TR.sub.P3 and
TR.sub.P4 are arranged in the horizontal direction while the two
triangular shapes TR.sub.P1 and TR.sub.P3 are arranged in the
vertical direction and two triangular shape patterns TR.sub.P2 and
TR.sub.P4 are arranged in the vertical direction.
[0016] FIG. 5 is an explanatory diagram illustrating radiation
direction 4 of beams reflected by a main reflector 2.
[0017] FIG. 6A is an explanatory diagram illustrating radiation
directions .theta..sub.1 and .theta..sub.2 of sidelobes of a
reflected beam of a primary radiator 1 labeled A4, FIG. 6B is an
explanatory diagram illustrating radiation directions .theta..sub.1
and .theta..sub.2 of sidelobes of a reflected beam of a primary
radiator 1 labeled B4, FIG. 6C is an explanatory diagram
illustrating radiation directions .theta..sub.1 and .theta..sub.2
of sidelobes of a reflected beam of a primary radiator 1 labeled
C2, and FIG. 6D is an explanatory diagram illustrating radiation
directions .theta..sub.1 and .theta..sub.2 of sidelobes of a
reflected beam of a primary radiator 1 labeled D2.
[0018] FIG. 7 is an explanatory diagram illustrating a simulation
result of a radiation pattern of a reflection beam of the primary
radiator 1 labeled C2.
[0019] FIG. 8 is an explanatory diagram illustrating a simulation
result of a radiation pattern of the reflection beam of the primary
radiator 1 labeled C2 in the case where an aperture shape of the
main reflector 2 is circular.
[0020] FIG. 9 is an explanatory diagram showing C/I values in the
case where the aperture shape of the main reflector 2 is a
parallelogram and in the case where it is circular.
[0021] FIG. 10 is a configuration diagram illustrating an antenna
apparatus according to Second Embodiment of the present
disclosure.
[0022] FIG. 11 is a diagram showing an illustrative example of
arrangement of primary radiators 1 of the antenna apparatus
according to Second Embodiment of the present disclosure.
[0023] FIG. 12 is an explanatory diagram illustrating radiation
directions .theta..sub.1, .theta..sub.2, and .theta..sub.3 of
sidelobes of a reflected beam of a primary radiator 1 labeled
A4.
[0024] FIG. 13 is a configuration diagram illustrating an antenna
apparatus according to Third Embodiment of the present
disclosure.
[0025] FIG. 14 is a diagram showing an illustrative example of
arrangement of primary radiators 1 of the antenna apparatus
according to Third Embodiment of the present disclosure.
[0026] FIG. 15 is an explanatory diagram illustrating radiation
directions .theta..sub.1, .theta..sub.2, and .theta..sub.3 of
sidelobes of a reflected beam of a primary radiator 1 labeled
C3.
[0027] FIG. 16 is a configuration diagram illustrating an antenna
apparatus according to Fourth Embodiment of the present
disclosure.
[0028] FIG. 17 is a configuration diagram illustrating an antenna
apparatus according to Fifth Embodiment of the present
disclosure.
DESCRIPTION OF EMBODIMENTS
[0029] To describe the present disclosure further in detail,
embodiments of the present disclosure will be described below with
reference to the accompanying drawings.
First Embodiment
[0030] FIG. 1 is a configuration diagram illustrating an antenna
apparatus according to First Embodiment of the present
disclosure.
[0031] In FIG. 1, each of primary radiators 1 is a radio wave
irradiation source for radiating a radio wave toward a main
reflector 2.
[0032] The primary radiators 1 are arranged such that a spillover
of the main reflector 2 is reduced and, in the example of FIG. 1,
are arranged near a focal point of the main reflector 2.
[0033] The main reflector 2 reflects radio waves radiated from the
plurality of primary radiators 1, and in the example of FIG. 1 the
shape of the main reflector 2 is a parabolid.
[0034] Reference numeral 3 illustrates an aperture shape when the
main reflector 2 is viewed from the front, and in the example of
FIG. 1 an aperture shape 3 of the main reflector 2 is a
parallelogram.
[0035] In First Embodiment, the plurality of primary radiators 1
are classified according to combination of frequency and
polarization of radiated radio waves, and a plurality of primary
radiators 1 belonging to the same class are arranged at positions
corresponding to vertexes of triangles in a repeated triangle
pattern in which a triangular shape is repeatedly arranged. Details
will be described later.
[0036] Furthermore, the shape of the main reflector 2 and the shape
and arrangement of the repeated triangle pattern are determined
such that a direction of a line segment passing through positions
corresponding to two vertexes in a triangle is different from a
radiation direction of a sidelobe of a radio wave that is radiated
from primary radiators 1 arranged at positions corresponding to the
vertexes and is reflected by the main reflector 2.
[0037] FIG. 2 is a diagram showing an illustrative example of
arrangement of the primary radiators 1 of the antenna apparatus
according to First Embodiment of the present disclosure.
[0038] FIG. 2 illustrates arrangement of the primary radiators 1 as
viewed from the front, and in the example of FIG. 2 sixteen primary
radiators 1 are arranged. However, this is merely an example, and
the number is not limited to sixteen.
[0039] An alphabet in the figure is a label representing a
combination of frequency and polarization of a radio wave radiated
from a primary radiator 1, and primary radiators 1 labeled with the
same alphabet use the same combination of frequency and
polarization.
[0040] FIG. 3 is an explanatory diagram illustrating an example of
combinations of frequency and polarization corresponding to
labels.
[0041] In FIG. 3, for example, combinations of two types of
polarizations P1 and P2 such as vertical polarization and
horizontal polarization and two types of frequencies F1 and F2 are
illustrated, and in FIG. 3 a total of four combinations are
described as an example.
[0042] The sixteen primary radiators 1 in FIG. 2 are classified
according to combination of frequency and polarization of radiated
radio waves, and primary radiators 1 labeled A1, A2, A3, and A4
belong to the same class, and primary radiators 1 labeled B1, B2,
B3, and B4 belong to the same class.
[0043] Primary radiators 1 labeled C1, C2, C3, and C4 belong to the
same class, and primary radiators 1 labeled D1, D2, D3, and D4
belong to the same class.
[0044] A plurality of primary radiators 1 belonging to the same
class is arranged at positions corresponding to vertexes of
triangles in a repeated triangle pattern in which one or more
triangular shapes are repeated.
[0045] Looking at the four primary radiators 1 labeled A1, A2, A3,
and A4 for example, the three primary radiators 1 labeled A1, A3,
and A4 are arranged in a triangular shape, and the three primary
radiators 1 labeled A1, A2, and A4 are also arranged in a
triangular shape.
[0046] That is, the four primary radiators 1 labeled A1, A2, A3,
and A4 are arranged at positions corresponding to vertexes of
triangles in a repeated triangle pattern TR.sub.Pattern in which a
triangular shape TR.sub.P1 and a triangular shape TR.sub.P2 are
arranged.
[0047] The triangular shape TR.sub.P1 is an arrangement of the
three primary radiators 1 labeled A1, A3, and A4, and the
triangular shape TR.sub.P2 is an arrangement of the three primary
radiators 1 labeled A1, A2, and A4. FIG. 2 illustrates an example
in which each of the triangles is an equilateral triangle.
[0048] In FIG. 2, an example of the repeated triangle pattern
TR.sub.Pattern in which the two triangular shapes TR.sub.P1 and
TR.sub.P2 are arranged in the horizontal direction in the figure is
illustrated; however, a repeated triangle pattern TR.sub.Pattern in
which three or more triangular shapes TR.sub.P are arranged in the
horizontal direction or a repeated triangle pattern TR.sub.Pattern
in which a plurality of triangular shapes TR.sub.P are arranged in
the vertical direction may be employed.
[0049] As shown in the example of FIG. 2, the four primary
radiators 1 labeled A1, A2, A3, and A4 are arranged so as to be in
contact with sides of the triangles, and thus the position of the
center of each of the primary radiators 1 is apart from the
position of a vertex of the triangles. Because the four primary
radiators 1 are arranged near the vertexes of the triangles, the
four primary radiators 1 are arranged at positions corresponding to
the vertexes of the triangles.
[0050] Note that it is understood without saying that the position
of the center of each of the primary radiators 1 may be arranged so
as to coincide with a vertex of the triangles.
[0051] FIG. 4 includes explanatory diagrams illustrating examples
of a repeated triangle pattern TR.sub.Pattern.
[0052] FIG. 4A is a diagram illustrating a repeated triangle
pattern TR.sub.Pattern in which three triangular shapes TR.sub.P1,
TR.sub.P2, and TR.sub.P3 are arranged in the horizontal
direction.
[0053] The triangular shape TR.sub.P1 is an arrangement of the
three primary radiators 1 labeled A1, A3, and A4, the triangular
shape TR.sub.P2 is an arrangement of the three primary radiators 1
labeled A1, A2, and A4, and the triangular shape TR.sub.P3 is an
arrangement of the three primary radiators 1 labeled A2, A4, and
A5.
[0054] FIG. 4B is a diagram illustrating a repeated triangle
pattern TR.sub.Pattern in which the two triangular shapes TR.sub.P1
and TR.sub.P2 are arranged in the horizontal direction and the two
triangular shapes TR.sub.P3 and TR.sub.P4 are arranged in the
horizontal direction, while the two triangular shapes TR.sub.P1 and
TR.sub.P2 are arranged in the vertical direction and two triangular
shapes TR.sub.P2 and TR.sub.P4 are arranged in the vertical
direction.
[0055] The triangular shape TR.sub.P1 is an arrangement of the
three primary radiators 1 labeled A1, A3, and A4, the triangular
shape TR.sub.P2 is an arrangement of the three primary radiators 1
labeled A1, A2, and A4, the triangular shape TR.sub.P3 is an
arrangement of the three primary radiators 1 labeled A3, A5, and
A6, and the triangular shape TR.sub.P4 is an arrangement of the
three primary radiators 1 labeled A3, A4, and A6.
[0056] As can be seen from FIG. 4, a repeated triangle pattern
TR.sub.Pattern of a desired shape can be created by repeating a
plurality of triangular shapes TR.sub.P in a desired direction.
[0057] In the above, the repeated triangle pattern TR.sub.Pattern
in which one or more triangular shapes are repeated has been
described focusing on the four primary radiators 1 labeled A1, A2,
A3, and A4. In the example of FIG. 2, arrangements of the primary
radiators 1 labeled B1, B2, B3, and B4 also form a repeated
triangle pattern TR.sub.Pattern in which the two triangular shapes
TR.sub.P are arranged in the horizontal direction.
[0058] Likewise, arrangements of the primary radiators 1 labeled
C1, C2, C3, and C4 also form a repeated triangle pattern
TR.sub.Pattern in which two triangular shapes TR.sub.P are arranged
in the horizontal direction, and arrangements of the primary
radiators 1 labeled D1, D2, D3, and D4 also form a repeated
triangle pattern TR.sub.Pattern in which two triangular shapes
TR.sub.P are arranged in the horizontal direction.
[0059] In the example of FIG. 2, since there are four combinations
of frequency and polarization of radiated radio waves, four
repeated triangle patterns TR.sub.Pattern each corresponding to one
of the combinations are arranged to be combined regularly, and the
overall arrangement shape of the sixteen primary radiators 1 has
the same parallelogram shape as that of the aperture shape 3 of the
main reflector 2.
[0060] Furthermore in the example of FIG. 2, given vertexes H, I,
J, and K of the parallelogram which is the aperture shape 3 of the
main reflector 2, interior angles .angle.IHK and .angle.IJK of the
parallelogram have 60 degrees, which are equal to an interior angle
of an equilateral triangle. Moreover, the sixteen primary radiators
1 are arranged such that a radio wave radiated from the primary
radiator 1 labeled C3 is irradiated near the vertex H, a radio wave
radiated from the primary radiator 1 labeled D4 is irradiated near
the vertex I, a radio wave radiated from the primary radiator 1
labeled B2 is irradiated near the vertex J, and a radio wave
radiated from the primary radiator 1 labeled A1 is irradiated near
the vertex K.
[0061] Also, focusing on the three primary radiators 1 labeled A1,
B1, and D1 out of the sixteen primary radiators 1, the three
primary radiators 1 are arranged in an equilateral triangle shape
without overlapping. This is to arrange beams densely, and the
equilateral triangle shape is known as a shape that enables the
densest arrangement of a circular aperture.
[0062] Next, operations will be described.
[0063] The sixteen primary radiators 1 radiate radio waves toward
the main reflector 2. Each of the radio waves radiated from the
primary radiators 1 is hereinafter referred to as a beam.
[0064] The main reflector 2 reflects beams radiated from the
sixteen primary radiators 1.
[0065] FIG. 5 is an explanatory diagram illustrating radiation
directions 4 of the beams reflected by the main reflector 2.
[0066] In FIG. 5, the horizontal axis represents the angle in a
horizontal plane, the vertical axis represents the angle in a
vertical plane, and a radiation direction 4 of a beam corresponds
to a service area of a radio wave.
[0067] Furthermore, a label attached to each of the radiation
directions 4 of the beams corresponds to a label labeled to each of
the primary radiators 1 illustrated in FIG. 2.
[0068] FIG. 6 includes explanatory diagrams illustrating radiation
directions .theta..sub.1 and .theta..sub.2 of sidelobes of a
reflection beam of a primary radiator 1.
[0069] Hereinafter, the expression "reflection beam of a primary
radiator 1" means a beam radiated from the primary radiator 1 and
then reflected by the main reflector 2.
[0070] FIG. 6A is an explanatory diagram illustrating radiation
directions .theta..sub.1 and .theta..sub.2 of sidelobes of a
reflection beam of the primary radiator 1 labeled A4, and FIG. 6B
is an explanatory diagram illustrating radiation directions
.theta..sub.1 and .theta..sub.2 of sidelobes of a reflection beam
of the primary radiator 1 labeled B4.
[0071] Furthermore, FIG. 6C is an explanatory diagram illustrating
radiation directions .theta..sub.1 and .theta..sub.2 of sidelobes
of a reflection beam of the primary radiator 1 labeled C2, and FIG.
6D is an explanatory diagram illustrating radiation directions
.theta..sub.1 and .theta..sub.2 of sidelobes of a reflection beam
of the primary radiator 1 labeled D2.
[0072] The radiation directions .theta..sub.1 and .theta..sub.2 of
sidelobes are determined by the aperture shape 3 of the main
reflector 2, and in a case where the aperture shape 3 of the main
reflector 2 is a parallelogram, each of the radiation directions
.theta..sub.1 and .theta..sub.2 is formed in the direction that is
perpendicular to associated opposing two sides of the
parallelogram.
[0073] Looking at the primary radiator 1 labeled A4 for example, as
illustrated in FIG. 6A, sidelobes are formed in a direction
.theta..sub.1 perpendicular to a line segment HI and a line segment
KJ of the parallelogram, while other sidelobes are formed in a
direction .theta..sub.2 perpendicular to a line segment HK and a
line segment IJ of the parallelogram.
[0074] Further looking at the primary radiator 1 labeled B4, as
illustrated in FIG. 6B, sidelobes are formed in a direction
.theta..sub.1 perpendicular to the line segment HI and the line
segment KJ of the parallelogram, while other sidelobes are formed
in a direction .theta..sub.2 perpendicular to the line segment HK
and the line segment IJ of the parallelogram.
[0075] Looking at the primary radiator 1 labeled C2, as illustrated
in FIG. 6C, sidelobes are formed in a direction .theta..sub.1
perpendicular to the line segment HI and the line segment KJ of the
parallelogram, while other sidelobes are formed in a direction
.theta..sub.2 perpendicular to the line segment HK and the line
segment IJ of the parallelogram.
[0076] Further looking at the primary radiator 1 labeled D2, as
illustrated in FIG. 6D, sidelobes are formed in a direction
.theta..sub.1 perpendicular to the line segment HI and the line
segment KJ of the parallelogram, while other sidelobes are formed
in a direction .theta..sub.2 perpendicular to the line segment HK
and the line segment IJ of the parallelogram.
[0077] Looking at the primary radiator 1 labeled A4 for example,
primary radiators 1 having the same combination of frequency and
polarization as that of a beam of the primary radiator 1 labeled A4
are the primary radiators 1 labeled A1, A2, and A3.
[0078] Therefore, out of beams reflected by the main reflector 2,
reflection beams of the primary radiators 1 labeled A1, A2, and A3
may be interfered by a reflection beam of the primary radiator 1
labeled A4.
[0079] However, in First Embodiment, since the overall arrangement
of the sixteen primary radiators 1 has the same parallelogram shape
as that of the aperture shape 3 of the main reflector 2, the
reflection beams of the primary radiators 1 labeled A1, A2, and A3
are not interfered by the reflection beam of the primary radiator 1
labeled A4.
[0080] That is, the primary radiator 1 labeled A4 is arranged at a
position corresponding to a vertex of the same equilateral triangle
as that of the primary radiators 1 labeled A1 and A2. Furthermore,
the primary radiator 1 labeled A4 is arranged at a position
corresponding to a vertex of the same equilateral triangle as that
of the primary radiators 1 labeled A1 and A3.
[0081] Suppose the position that corresponds to the vertex of the
equilateral triangle(s) at which the primary radiator 1 labeled A4
is arranged is a base point. Then, directions of line segments
passing through the base point and the positions corresponding to
the other vertexes of the equilateral triangles are given as a
direction .alpha..sub.1, a direction .alpha..sub.2, and a direction
.alpha..sub.3 as illustrated in FIG. 6A.
[0082] Specifically, a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled A4 and
the arrangement position of the primary radiator 1 labeled A1 is
.alpha..sub.1, and a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled A4 and
the arrangement position of the primary radiator 1 labeled A2 is
.alpha..sub.2. Moreover, a direction of a line segment passing
through the arrangement position of the primary radiator 1 labeled
A4 and the arrangement position of the primary radiator 1 labeled
A3 is .alpha..sub.3.
[0083] Because the directions .alpha..sub.1, .alpha..sub.2, and
.alpha..sub.3 of the line segments are different from the radiation
directions .theta..sub.1 and .theta..sub.2 of the sidelobes,
reflection beams of the primary radiators 1 labeled A1, A2, and A3
are not interfered by the reflection beam of the primary radiator 1
labeled A4.
[0084] Looking at the primary radiator 1 labeled C2 for example,
primary radiators 1 having the same combination of frequency and
polarization as that of a beam of the primary radiator 1 labeled C2
are the primary radiators 1 labeled C1, C3, and C4.
[0085] Therefore, out of beams reflected by the main reflector 2,
reflection beams of the primary radiators 1 labeled C1, C3, and C4
may be interfered by a reflection beam of the primary radiator 1
labeled C2.
[0086] However, in First Embodiment, since the overall arrangement
of the sixteen primary radiators 1 has the same parallelogram shape
as that of the aperture shape 3 of the main reflector 2, the
reflection beams of the primary radiators 1 labeled C1, C3, and C4
are not interfered by the reflection beam of the primary radiator 1
labeled C2.
[0087] That is, the primary radiator 1 labeled C2 is arranged at a
position corresponding to a vertex of the same equilateral triangle
as that of the primary radiators 1 labeled C1 and C4.
[0088] Suppose the position that corresponds to the vertex of the
equilateral triangle at which the primary radiator 1 labeled C2 is
arranged is a base point. Then, directions of line segments passing
through the base point and the positions corresponding to the other
vertexes of the equilateral triangle are given as a direction
.alpha..sub.3 and a direction .alpha..sub.2 as illustrated in FIG.
6C.
[0089] Specifically, a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled C2 and
the arrangement position of the primary radiator 1 labeled C1 is
.alpha..sub.3, and a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled C2 and
the arrangement position of the primary radiator 1 labeled C4 is
.alpha..sub.2.
[0090] Although the primary radiator 1 with label C2 and the
primary radiator 1 labeled C3 are not located at positions
corresponding to vertexes of the same equilateral triangle, a
direction of a line segment passing through the arrangement
position of the primary radiator 1 labeled C2 and the arrangement
position of the primary radiator 1 labeled C3 is .alpha..sub.4.
[0091] Because the directions .alpha..sub.2, .alpha..sub.3, and
.alpha..sub.4 of the line segments are different from the radiation
directions .theta..sub.1 and .theta..sub.2 of the sidelobes,
reflection beams of the primary radiators 1 labeled C1, C3, and C4
are not interfered by the reflection beam of the primary radiator 1
labeled C2.
[0092] Looking at the primary radiator 1 labeled B4, a similar
relation to the case of looking at the primary radiator 1 labeled
A4 applies, and reflection beams of the primary radiators 1 labeled
B1, B2, and B3 are not interfered by a reflection beam of the
primary radiator 1 labeled B4.
[0093] In addition, looking at the primary radiator 1 labeled D2, a
similar relation to the case of looking at the primary radiator 1
labeled C2 applies, and reflection beams of the primary radiators 1
labeled D1, D3, and D4 are not interfered by a reflection beam of
the primary radiator 1 labeled D2.
[0094] FIG. 7 is an explanatory diagram illustrating a simulation
result of a radiation pattern of a reflection beam of the primary
radiator 1 labeled C2.
[0095] In FIG. 7, the horizontal axis represents the angle in a
horizontal plane, and the vertical axis represents the angle in a
vertical plane. Since the aperture shape 3 of the main reflector 2
is a parallelogram, sidelobes due to the reflection beam of the
primary radiator 1 labeled C2 are formed in two directions.
[0096] However, as described above, it is understood that the
reflection beams of the primary radiators 1 labeled C1, C3, and C4
are not interfered by the reflection beam of the primary radiator 1
labeled C2 since the directions .alpha..sub.2, .alpha..sub.3, and
.alpha..sub.4 of the line segments are different from the radiation
directions .theta..sub.1 and .theta..sub.2 of the sidelobes.
[0097] FIG. 8 is an explanatory diagram illustrating a simulation
result of a radiation pattern of the reflection beam of the primary
radiator 1 labeled C2 in the case where the aperture shape of the
main reflector 2 is circular.
[0098] In FIG. 8, the horizontal axis represents the angle in a
horizontal plane, and the vertical axis represents the angle in a
vertical plane.
[0099] In the case where the aperture shape of the main reflector 2
is circular, sidelobes due to the reflection beam of the primary
radiator 1 labeled C2 are concentrically formed around the
direction of the main beam. It can be understood that as a result
of the above the sidelobes due to the reflection beam of the
primary radiator 1 labeled C2 arrive at service areas of reflection
beams of the primary radiators 1 labeled C1, C3, and C4, and thus
the reflection beams of the primary radiators 1 labeled C1, C3, and
C4 are interfered by the reflection beam of the primary radiator 1
labeled C2.
[0100] Note that, in the case where the aperture shape of the main
reflector 2 is rectangular, sidelobes are formed in directions each
perpendicular to two opposing sides of the rectangle. Therefore,
the reflection beams of the primary radiators 1 labeled C3 and C4
are not interfered by the reflection beam of the primary radiator 1
labeled C2; however, the reflection beam of the primary radiator 1
labeled C1 is interfered by the reflection beam of the primary
radiator 1 labeled C2 since the sidelobes due to the reflection
beam of the primary radiator 1 labeled C2 arrive at the service
area of the reflection beam of the primary radiator 1 labeled
C1.
[0101] FIG. 9 is an explanatory diagram showing C/I values in the
case where the aperture shape of the main reflector 2 is a
parallelogram and in the case where it is circular.
[0102] A C/I in the case where the aperture shape 3 of the main
reflector 2 is a parallelogram is -28.5 dB, and a C1 in the case
where the aperture shape of the main reflector is circular is -23.2
dB, and therefore the C/I is improved by 5.3 dB in the case where
the aperture shape 3 of the main reflector 2 is a parallelogram
than in the case where the aperture shape is circular.
[0103] As is apparent from the above, according to First
Embodiment, the plurality of primary radiators 1 is classified by
combination of frequency and polarization of the radiated radio
waves, a plurality of primary radiators belonging to the same class
is arranged at positions corresponding to vertexes of one of
triangles in a repeated triangle pattern TR.sub.Pattern, and the
shape of the main reflector 2 and the shape and arrangement of the
repeated triangle pattern TR.sub.Pattern are determined such that a
direction of a line segment passing through positions corresponding
to two vertexes in the triangle is different from a radiation
direction of a sidelobe of a radio wave reflected by the main
reflector 2 after having been radiated from a primary radiator 1
arranged at a position corresponding to the vertexes. Therefore,
the effect of suppressing interference among all the beams having
the same combination of frequency and polarization can be
obtained.
[0104] According to First Embodiment, the aperture shape 3 of the
main reflector 2 is a parallelogram, and one or more triangular
shapes are repeated such that the repeated triangle pattern
TR.sub.Pattern has the same shape as that of the aperture shape 3
of the main reflector 2, and thus a major part of radio waves
radiated from the plurality of primary radiators 1 is reflected by
the main reflector 2, thereby enabling mitigation of radio waves
not reflected by the main reflector 2. Therefore, the utilization
rate of radio waves is increased, and the gain of the antenna
apparatus can be increased.
[0105] In First Embodiment, the example has been illustrated in
which two interior angles of the parallelogram which is the
aperture shape 3 of the main reflector 2, that is, the .angle.IHK
and the .angle.IJK are 60 degrees, which are equal to the interior
angles of an equilateral triangle; however, even in the case where
the .angle.IHK and the .angle.IJK of the parallelogram deviate from
60 degrees by about 20%, interference among all the beams having
the same combination of frequency and polarization can be
suppressed. That is, even in the case where the aperture shape 3 of
the main reflector 2 is not a perfect parallelogram, interference
among all the beams having the same combination of frequency and
polarization can be suppressed.
[0106] In First Embodiment, the example in which the three primary
radiators 1 are arranged in a triangular shape has been
illustrated; however depending on a required service area, one or
two primary radiators 1 may be thinned out from those in a
triangular shape TR.sub.P from among a plurality of triangular
shapes TR.sub.P.
[0107] Furthermore, it is only required that an arrangement of the
repeated triangle pattern TR.sub.Pattern is in conformity with the
arrangement of FIG. 2 for example, and the shape of the repeated
triangle pattern TR.sub.Pattern is not required to be a
parallelogram as a result of thinning out some of the primary
radiators 1.
[0108] In First Embodiment, the example in which there are four
combinations of frequency and polarization has been illustrated;
however, this is merely an example, and the number of combinations
of frequency and polarization may be three or seven, for
example.
[0109] In First Embodiment, the aperture shape 3 of the main
reflector 2 is a parallelogram; however, vertexes of the
parallelogram are not required to be angular and may be, for
example, rounded or chamfered.
Second Embodiment
[0110] In Embodiment 1, the aperture shape 3 of the main reflector
2 is a parallelogram. In Second Embodiment, an example in which an
aperture shape of the main reflector is a hexagon will be
described.
[0111] In the case where the aperture shape 3 of the main reflector
2 is a parallelogram, for example when the antenna apparatus is
mounted on a satellite, useless space is created, and the space
cannot be effectively used, which may deteriorate mountability to
the satellite.
[0112] Accordingly, in Second Embodiment, an example will be
described in which a hexagon is used as a shape that enables more
effective use of the space.
[0113] FIG. 10 is a configuration diagram illustrating an antenna
apparatus according to Second Embodiment of the present disclosure.
In FIG. 10, the same reference numeral as that in FIG. 1 represents
the same or a corresponding part and thus descriptions thereon are
omitted.
[0114] A main reflector 5 is a reflector which reflects radio waves
radiated from a plurality of primary radiators 1.
[0115] Reference numeral 6 denotes an aperture shape of the main
reflector 5 when viewed from the front, and in the example of FIG.
10, an aperture shape 6 of the main reflector 5 is a hexagon.
[0116] In Second Embodiment, it is assumed that the aperture shape
6 of the main reflector 5 is a regular hexagon.
[0117] FIG. 11 is a diagram showing an illustrative example of
arrangement of the primary radiators 1 of the antenna apparatus
according to Second Embodiment of the present disclosure.
[0118] FIG. 11 illustrates an arrangement of the primary radiators
1 as viewed from the front, and in the example of FIG. 11 nineteen
primary radiators 1 are arranged. However, this is merely an
example, and the number is not limited to nineteen.
[0119] An alphabet in the figure is a label representing a
combination of frequency and polarization of a radio wave radiated
from a primary radiator 1, and primary radiators 1 labeled with the
same alphabet use the same combination of frequency and
polarization.
[0120] The nineteen primary radiators 1 in FIG. 11 are classified
by combinations of frequency and polarization of radiated radio
waves, and primary radiators 1 labeled A1, A2, A3, A4, A5, A6, and
A7 belong to the same class, and primary radiators 1 labeled B1,
B2, B3, and B4 belong to the same class.
[0121] Primary radiators 1 labeled C1, C2, C3, and C4 belong to the
same class, and primary radiators 1 labeled D1, D2, D3, and D4
belong to the same class.
[0122] A plurality of primary radiators 1 belonging to the same
class is arranged at positions corresponding to vertexes of each of
triangles in a repeated triangle pattern in which one or more
triangular shapes are repeated.
[0123] Looking at the four primary radiators 1 labeled C1, C2, C3,
and C4 for example, the three primary radiators 1 labeled C1, C2,
and C3 are arranged in a triangular shape, and the three primary
radiators 1 labeled C2, C3, and C4 are also arranged in a
triangular shape.
[0124] That is, the four primary radiators 1 labeled C1, C2, C3,
and C4 are arranged at positions corresponding to vertexes of each
of triangles in a repeated triangle pattern TR.sub.Pattern in which
a triangular shape TR.sub.P1 and a triangular shape TR.sub.P2 are
arranged.
[0125] The triangular shape TR.sub.P1 is an arrangement of the
three primary radiators 1 labeled C1, C2, and C3, and the
triangular shape TR.sub.P2 is an arrangement of the three primary
radiators 1 labeled C2, C3, and C4. FIG. 11 illustrates an example
in which each of the triangles is an equilateral triangle.
[0126] In FIG. 11, an example of the repeated triangle pattern
TR.sub.Pattern in which the two triangular shapes TR.sub.P1 and
TR.sub.P2 are arranged in the horizontal direction in the figure is
illustrated; however, a repeated triangle pattern TR.sub.Pattern in
which three or more triangular shapes TR.sub.P are arranged in the
horizontal direction or a repeated triangle pattern TR.sub.Pattern
in which a plurality of triangular shapes TR.sub.P are arranged in
the vertical direction may be employed.
[0127] Next, operations will be described.
[0128] The nineteen primary radiators 1 radiate beams toward the
main reflector 5.
[0129] The main reflector 5 reflects the beams radiated from the
nineteenth primary radiators 1.
[0130] FIG. 12 is an explanatory diagram illustrating radiation
directions .theta..sub.1, .theta..sub.2, and .theta..sub.3 of
sidelobes of a reflection beam of the primary radiator 1 labeled
A4.
[0131] The radiation directions .theta..sub.1, .theta..sub.2, and
.theta..sub.3 of the sidelobes are determined by the aperture shape
6 of the main reflector 5, and in the case where the aperture shape
of the main reflector 5 is a regular hexagon, the sidelobes are
formed in directions each perpendicular to two sides of the regular
hexagon opposing each other.
[0132] That is, sidelobes are formed in the direction .theta..sub.1
perpendicular to both a line segment LM and a line segment OP of
the regular hexagon, sidelobes are formed in the direction
.theta..sub.2 perpendicular to both a line segment MN and a line
segment PQ of the regular hexagon, and sidelobes are formed in the
direction .theta..sub.3 perpendicular to both a line segment NO and
a line segment QL of the regular hexagon.
[0133] Looking at the primary radiator 1 labeled A4 for example,
primary radiators 1 having the same combination of frequency and
polarization as that of a beam of the primary radiator 1 labeled A4
are the primary radiators 1 labeled A1, A2, A3, A5, A6, and A7.
[0134] Thus, out of beams reflected by the main reflector 5,
reflection beams of the primary radiators 1 labeled A1, A2, A3, A5,
A6, and A7 may be interfered by a reflection beam of the primary
radiator 1 labeled A4.
[0135] However, in Second Embodiment, since the overall arrangement
of the nineteen primary radiators 1 has the same regular hexagon
shape as that of the aperture shape 6 of the main reflector 5, the
reflection beams of the primary radiators 1 labeled A1, A2, A3, A5,
A6, and A7 are not interfered by the reflection beam of the primary
radiator 1 labeled A4.
[0136] That is, the primary radiator 1 labeled A4 is arranged at a
position corresponding to a vertex of the same equilateral triangle
as that of the primary radiators 1 labeled A1 and A2, for example.
Furthermore, the primary radiator 1 labeled A4 is arranged at a
position corresponding to a vertex of the same equilateral triangle
as that of the primary radiators 1 labeled A1 and A3.
[0137] Directions of line segments passing through a base point of
the position corresponding to the vertex of the equilateral
triangles, in which the primary radiator 1 labeled A4 is arranged,
and the positions corresponding to the other vertexes of the
equilateral triangles are given as a direction .alpha..sub.1, a
direction .alpha..sub.2, and a direction .alpha..sub.3 as
illustrated in FIG. 12.
[0138] Specifically, a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled A4 and
the arrangement positions of the primary radiators 1 labeled A1 and
A7 is .alpha..sub.1, and a direction of a line segment passing
through the arrangement position of the primary radiator 1 labeled
A4 and the arrangement positions of the primary radiators 1 labeled
A2 and A6 is .alpha..sub.2. Moreover, a direction of a line segment
passing through the arrangement position of the primary radiator 1
labeled A4 and the arrangement positions of the primary radiators 1
labeled A3 and A5 is .alpha..sub.3.
[0139] Because the directions .alpha..sub.1, .alpha..sub.2, and
.alpha..sub.3 of the line segments are different from the radiation
directions .theta..sub.1, .theta..sub.2, and .theta..sub.3 of the
sidelobes, reflection beams of the primary radiators 1 labeled A1,
A2, A3, A5, A6, and A7 are not interfered by the reflection beam of
the primary radiator 1 labeled A4.
[0140] As is apparent from the above, according to Second
Embodiment, the plurality of primary radiators 1 is classified by
combination of frequency and polarization of the radiated radio
waves, a plurality of primary radiators belonging to the same class
is arranged at positions corresponding to vertexes of one of
triangles in a repeated triangle pattern TR.sub.Pattern and the
shape of the main reflector 5 and the shape and arrangement of the
repeated triangle pattern TR.sub.Pattern are determined such that a
direction of a line segment passing through positions corresponding
to two vertexes in the triangle is different from a radiation
direction of a sidelobe of a radio wave reflected by the main
reflector 5 after having been radiated from a primary radiator 1
arranged at a position corresponding to the vertexes. Therefore,
the effect of suppressing interference among all the beams having
the same combination of frequency and polarization can be
obtained.
[0141] Furthermore, according to Second Embodiment, the aperture
shape 6 of the main reflector 5 is a regular hexagon, and one or
more triangular shapes are repeated such that the repeated triangle
pattern TR.sub.Pattern has the same shape as that of the aperture
shape 6 of the main reflector 5, and thus a major part of radio
waves radiated from the plurality of primary radiators 1 is
reflected by the main reflector 5, thereby enabling mitigation of
radio waves not reflected by the main reflector 5. Therefore, the
utilization rate of radio waves is increased, and the gain of the
antenna apparatus can be increased. In addition, mountability to a
satellite can be enhanced for example compared to First
Embodiment.
[0142] In Second Embodiment, the example has been illustrated in
which interior angles of the hexagon which is the aperture shape 6
of the main reflector 5 are 120 degrees; however, even in the case
where the interior angles deviate from 120 degrees by about 20%,
interference among all the beams having the same combination of
frequency and polarization can be suppressed. That is, even in the
case where the aperture shape 6 of the main reflector 5 is not a
perfect regular hexagon, interference among all the beams having
the same combination of frequency and polarization can be
suppressed.
[0143] In Second Embodiment, the example in which the three primary
radiators 1 are arranged in a triangular shape has been
illustrated; however depending on a required service area, one or
two primary radiators 1 may be thinned out from those in a
triangular shape TR.sub.P from among a plurality of triangular
shapes TR.sub.P.
[0144] Furthermore, it is only required that an arrangement of the
repeated triangle pattern TR.sub.Pattern is in conformity with the
arrangement of FIG. 11 for example, and the shape of the repeated
triangle pattern TR.sub.Pattern is not required to be a regular
hexagon as a result of thinning out some of the primary radiators
1.
[0145] In Second Embodiment, the example in which there are four
combinations of frequency and polarization has been illustrated;
however, this is merely an example, and the number of combinations
of frequency and polarization may be three or seven, for
example.
[0146] In Second Embodiment, the aperture shape 6 of the main
reflector 5 is a regular hexagon; however, vertexes of the regular
hexagon are not required to be angular and may be, for example,
rounded or chamfered.
Third Embodiment
[0147] In First Embodiment, the aperture shape 3 of the main
reflector 2 is a parallelogram. In Third Embodiment, an example in
which an aperture shape of the main reflector is triangular will be
described.
[0148] FIG. 13 is a configuration diagram illustrating an antenna
apparatus according to Third Embodiment of the present invention.
In FIG. 13, the same reference numeral as that in FIG. 1 represents
the same or a corresponding part and thus descriptions thereon are
omitted.
[0149] A main reflector 7 is a reflector which reflects radio waves
radiated from a plurality of primary radiators 1.
[0150] Reference numeral 8 denotes an aperture shape of the main
reflector 7 when viewed from the front, and in the example of FIG.
13, the aperture shape 8 of the main reflector 7 is triangular.
[0151] In Third Embodiment, it is assumed that the aperture shape 8
of the main reflector 7 is an equilateral triangle.
[0152] FIG. 14 is a diagram showing an illustrative example of
arrangement of the primary radiators 1 of the antenna apparatus
according to Third Embodiment of the present disclosure.
[0153] FIG. 14 illustrates arrangement of the primary radiators 1
as viewed from the front, and in the example of FIG. 14 fifteen
primary radiators 1 are arranged. However, this is merely an
example, and the number is not limited to fifteen.
[0154] An alphabet in the figure is a label representing a
combination of frequency and polarization of a radio wave radiated
from a primary radiator 1, and primary radiators 1 labeled by the
same alphabet use the same combination of frequency and
polarization.
[0155] The fifteen primary radiators 1 in FIG. 14 are classified by
combination of frequency and polarization of radiated radio waves,
and primary radiators 1 labeled A1, A2, A3, A4, A5, and A6 belong
to the same class, and primary radiators 1 labeled B1, B2, and B3
belong to the same class.
[0156] Primary radiators 1 labeled C1, C2, and C3 belong to the
same class, and primary radiators 1 labeled D1, D2, and D3 belong
to the same class.
[0157] A plurality of primary radiators 1 belonging to the same
class is arranged at positions corresponding to vertexes of each of
triangles in a repeated triangle pattern in which one or more
triangular shapes are repeated.
[0158] Looking at the six primary radiators 1 labeled A1, A2, A3,
A4, A5, and A6 for example, the three primary radiators 1 labeled
A1, A2, and A3 are arranged in a triangular shape, and the three
primary radiators 1 labeled A2, A4, and A5 are also arranged in a
triangular shape. The three primary radiators 1 labeled A2, A3, and
A5 are arranged in a triangular shape, and the three primary
radiators 1 labeled A3, A5, and A6 are arranged in a triangular
shape.
[0159] That is, the six primary radiators labeled A1, A2, A3, A4,
A5, and A6 are arranged at positions corresponding to vertexes of
each of triangles in a repeated triangle pattern TR.sub.Pattern in
which a triangular shape TR.sub.P1, a triangular shape TR.sub.P2, a
triangular shape TR.sub.P3, and a triangular shape TR.sub.P4 are
arranged.
[0160] The triangular shape TR.sub.P1 is an arrangement of the
three primary radiators 1 labeled A1, A2, and A3, the triangular
shape TR.sub.P2 is an arrangement of the three primary radiators 1
labeled A2, A4, and A5, the triangular shape TR.sub.P3 is an
arrangement of the three primary radiators 1 labeled A2, A3, and
A5, and the triangular shape TR.sub.P4 is an arrangement of the
three primary radiators 1 labeled A3, A5, and A6. FIG. 14
illustrates an example in which each of the triangles is an
equilateral triangle.
[0161] In FIG. 14, an example of the repeated triangle pattern
TR.sub.Pattern in which the three triangular shapes TR.sub.P2,
TR.sub.P 3, and TR.sub.P4 are arranged in the horizontal direction
in the figure and the triangular shapes TR.sub.P1, TR.sub.P2,
TR.sub.P3, and TR.sub.4 are arranged in the vertical direction in
the figure is illustrated; however, the present invention is not
limited thereto, and the number of repetitive patterns in the
horizontal direction and the vertical direction may be any
number.
[0162] Next, operations will be described.
[0163] The fifteen primary radiators 1 radiate beams toward the
main reflector 7.
[0164] The main reflector 7 reflects the beams radiated from the
fifteenth primary radiators 1.
[0165] FIG. 15 is an explanatory diagram illustrating radiation
directions .theta..sub.1, .theta..sub.2, and .theta..sub.3 of
sidelobes of a reflection beam of the primary radiator 1 labeled
C3.
[0166] The radiation directions .theta..sub.1, .theta..sub.2, and
.theta..sub.3 of the sidelobes are determined by the aperture shape
8 of the main reflector 7, and in the case where the aperture shape
8 of the main reflector 7 is an equilateral triangle, the sidelobes
are formed in directions each perpendicular to one side of the
equilateral triangle.
[0167] That is, sidelobes are formed in the direction .theta..sub.1
perpendicular to a line segment TR of the equilateral triangle,
sidelobes are formed in the direction .theta..sub.2 perpendicular
to a line segment RS of the equilateral triangle, and sidelobes are
formed in the direction .theta..sub.3 perpendicular to a line
segment ST of the equilateral triangle.
[0168] Looking at the primary radiator 1 labeled C3 for example,
primary radiators 1 having the same combination of frequency and
polarization as that of a reflection beam of the primary radiator 1
labeled C3 are the primary radiators 1 labeled C1 and C2.
[0169] Thus, out of beams reflected by the main reflector 7,
reflection beams of the primary radiators 1 labeled C1 and C2 may
be interfered by a reflection beam of the primary radiator 1
labeled C3.
[0170] However, in Third Embodiment, because the overall
arrangement of the fifteen primary radiators 1 has the same
equilateral triangle shape as that of the aperture shape 8 of the
main reflector 7, the reflection beams of the primary radiators 1
labeled C1 and C2 are not interfered by the reflection beam of the
primary radiator 1 labeled C3.
[0171] That is, the primary radiator 1 labeled C3 is arranged at a
position corresponding to a vertex of the same equilateral triangle
as that of the primary radiators 1 labeled C1 and C2.
[0172] Directions of line segments passing through a base point of
the position corresponding to the vertex of the equilateral
triangle, in which the primary radiator 1 labeled C3 is arranged,
and the positions corresponding to the other vertexes of the
equilateral triangle are given as a direction .alpha..sub.1 and a
direction .alpha..sub.2 as illustrated in FIG. 15.
[0173] Specifically, a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled C3 and
the arrangement position of the primary radiator 1 labeled C1 is
.alpha..sub.1, and a direction of a line segment passing through
the arrangement position of the primary radiator 1 labeled C3 and
the arrangement position of the primary radiator 1 labeled C2 is
.alpha..sub.2.
[0174] Here, because the directions .alpha..sub.1 and .alpha..sub.2
of the line segments are different from the radiation directions
.theta..sub.1, .theta..sub.2, and .theta..sub.3 of the sidelobes,
the reflection beams of the primary radiators 1 labeled C1 and C2
are not interfered by the reflection beam of the primary radiator 1
labeled C3.
[0175] As is apparent from the above, according to Third
Embodiment, the plurality of primary radiators 1 is classified by
combinations of frequency and polarization of the radiated radio
waves, a plurality of primary radiators belonging to the same class
is arranged at positions corresponding to vertexes of one of
triangles in a repeated triangle pattern TR.sub.Pattern, and the
shape of the main reflector 7 and the shape and arrangement of the
repeated triangle pattern TR.sub.Pattern are determined such that a
direction of a line segment passing through positions corresponding
to two vertexes in the triangle is different from a radiation
direction of a sidelobe of a radio wave reflected by the main
reflector 7 after having been radiated from a primary radiator 1
arranged at a position corresponding to the vertexes. Therefore,
the effect of suppressing interference among all the beams having
the same combination of frequency and polarization can be
obtained.
[0176] Furthermore, according to Third Embodiment, the aperture
shape 8 of the main reflector 7 is a equilateral triangle, and one
or more triangular shapes are repeated such that the repeated
triangle pattern TR.sub.Pattern has the same shape as that of the
aperture shape 8 of the main reflector 7, and thus a major part of
radio waves radiated from the plurality of primary radiators 1 is
reflected by the main reflector 7, thereby enabling mitigation of
radio waves not reflected by the main reflector 7. Therefore, the
utilization rate of radio waves is increased, and the gain of the
antenna apparatus can be increased.
[0177] In Third Embodiment, the example has been illustrated in
which interior angles of the triangle which is the aperture shape 8
of the main reflector 7 are 60 degrees; however, even in the case
where the interior angles deviate from 60 degrees by about 20%,
interference among all the beams having the same combination of
frequency and polarization can be suppressed. That is, even in the
case where the aperture shape 8 of the main reflector 7 is not a
perfect equilateral triangle, interference among all the beams
having the same combination of frequency and polarization can be
suppressed.
[0178] In Third Embodiment, the example in which the three primary
radiators 1 are arranged in a triangular shape has been
illustrated; however depending on a required service area, one or
two primary radiators 1 may be thinned out from those in a
triangular shape TR.sub.P from among a plurality of triangular
shapes TR.sub.P.
[0179] Furthermore, it is only required that an arrangement of the
repeated triangle pattern TR.sub.Pattern is in conformity with the
arrangement of FIG. 14 for example, and the shape of the repeated
triangle pattern TR.sub.Pattern is not required to be a equilateral
triangle as a result of thinning out some of the primary radiators
1.
[0180] In Third Embodiment, the example in which there are four
combinations of frequency and polarization has been illustrated;
however, this is merely an example, and the number of combinations
of frequency and polarization may be three or seven, for
example.
[0181] In Third Embodiment, the aperture shape 8 of the main
reflector 7 is an equilateral triangle; however, vertexes of the
equilateral triangle are not required to be angular and may be, for
example, rounded or chamfered.
Fourth Embodiment
[0182] In First to Third Embodiments, each of the primary radiators
1 radiates one beam to the main reflectors 2, 5, and 7; however, a
plurality of radiating elements may radiate one beam to the main
reflector 2, 5, or 7.
[0183] FIG. 16 is a configuration diagram illustrating an antenna
apparatus according to a fourth embodiment of the present
disclosure. In FIG. 16, the same reference numeral as that in FIG.
1 represents the same or a corresponding part and thus descriptions
thereon are omitted.
[0184] Each of primary radiators 1 includes a plurality of
radiating elements 9.
[0185] In the antenna apparatus of FIG. 16, for simplicity of
explanation, an example in which three primary radiators are
mounted is illustrated. However, in practice, a plurality of
primary radiators 1 for radiating radio waves having the same
combination of frequency and polarization is mounted, and a
plurality of primary radiators 1 for radiating radio waves having
different combinations of frequency and polarization is also
mounted. Thus, also in the antenna apparatus of FIG. 16, sixteen
primary radiators 1 are mounted for example like the antenna
apparatus of FIG. 1 according to First Embodiment.
[0186] However, the number of primary radiators 1 and the number of
radiating elements included in each of the primary radiators 1 may
be any number.
[0187] A beam forming circuit 10 is a feeding circuit for exciting
a plurality of radiating elements 9 in the primary radiators 1.
[0188] The beam forming circuit 10 excites four radiating elements
9 such that radio waves having the same combination of frequency
and polarization are radiated from the four radiating elements 9
belonging to the same primary radiator 1 while exciting each group
of four radiating elements 9 belonging to the three primary
radiators 1 such that combinations of frequency and the
polarization of radio waves radiated from the three primary
radiators 1 are different.
[0189] In the beam forming circuit 10, an excitation coefficient is
designed for each of the radiating elements 9, and in the case
where the direction of beams radiated from the three primary
radiators 1 are fixed, a signal capable of implementing the
excitation coefficient is fed to the radiating element 9.
[0190] In the case where the direction of beams radiated from the
three primary radiators 1 is variable, the beam forming circuit 10
includes phase shifters for adjusting the phase of a signal output
to each of the plurality of radiating elements 9 and a variable
gain amplifier(s) for adjusting the amplitude of a signal output to
the plurality of radiating elements 9, to adjust excitation
coefficients of the radiating elements 9 with the phase shifters
and the variable gain amplifier(s).
[0191] As a result, the radiation direction of a beam reflected by
the main reflector 2, a range of a service area of the beam, and
the like can be variable.
[0192] As is clear from the above, according to Fourth Embodiment,
since the beam forming circuit 10 for exciting the plurality of
radiating elements 9 is included, the effect of suppressing
interference among all the beams having the same combination of
frequency and polarization can be obtained like in First Embodiment
described above as well as the effect of enhancing the degree of
freedom of the radiation direction or other features of the
beam.
[0193] In Fourth Embodiment, the plurality of radiating elements 9
and the beam forming circuit 10 are used for the antenna apparatus
of First Embodiment in which the aperture shape 3 of the main
reflector 2 is a parallelogram; however, the plurality of radiating
elements and the beam forming circuit 10 may be used for the
antenna apparatus in which the aperture shape 6 of the main
reflector 5 is a regular hexagon as in Second Embodiment or the
antenna apparatus in which the aperture shape 8 of the main
reflector 7 is an equilateral triangle as in Third Embodiment.
Fifth Embodiment
[0194] In First to Fourth Embodiments, the plurality of primary
radiators 1 radiate beams to the main reflectors 2, 5, and 7;
however, the beams radiated from the plurality of primary radiators
1 may be radiated toward the main reflector 2, 5, or 7 via a
secondary reflector.
[0195] FIG. 17 is a configuration diagram illustrating an antenna
apparatus according to Fifth Embodiment of the present disclosure.
In FIG. 17, the same reference numeral as that in FIG. 1 represents
the same or a corresponding part and thus descriptions thereon are
omitted.
[0196] A secondary reflector 11 is a reflector which reflects radio
waves radiated from a plurality of primary radiators 1 toward a
main reflector 2, and in the example of FIG. 17, the secondary
reflector 11 is a Cassegrain type reflector having a mirror surface
of a hyperboloid of revolution.
[0197] Even in the case where the secondary reflector 11 reflects
the beams radiated from the plurality of primary radiators 1 toward
the main reflector 2, interference among all the beams having the
same combination of frequency and polarization can be suppressed
like in First Embodiment described above.
[0198] Here, the secondary reflector 11 of a Cassegrain type having
a mirror surface of a hyperboloid of revolution is described as an
example; however, a secondary reflector 11 of a Gregorian type
having a mirror surface of an ellipsoid of revolution may be used.
Alternatively, a secondary reflector 11 having a flat mirror
surface may be used.
[0199] Moreover, the secondary reflector 11 may include a plurality
of reflectors.
[0200] In Fifth Embodiment, the secondary reflector 11 is used for
the antenna apparatus of First Embodiment; however, the secondary
reflector 11 may be used for the antenna apparatuses of Second to
Fourth Embodiments described above.
[0201] Note that, within the scope of the present invention,
Embodiments may be combined freely, modifications may be made to
any component of Embodiments, or omission of any component in
Embodiments may be made.
INDUSTRIAL APPLICABILITY
[0202] Antenna apparatuses disclosed in the present disclosure is
suitable for antenna apparatuses with high gain and low
interference.
REFERENCE SIGNS LIST
[0203] 1: Primary radiator, 2: Main reflector, 3: Aperture shape of
the main reflector, 4: Radiation direction of beam, 5: Main
reflector, 6: Aperture shape of main reflector, 7: Main reflector,
8: Aperture shape of main reflector, 9: Radiating element, 10: Beam
forming circuit, 11: Secondary reflector.
* * * * *